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Author Correction: Persistent and reversible solid iodine electrodeposition in nanoporous carbons
Correction to: Nature Communications https://doi.org/10.1038/s41467-020-18610-6, published online 24 September 2020
Persistent and reversible solid iodine electrodeposition in nanoporous carbons
Aqueous iodine based electrochemical energy storage is considered a potential candidate to improve sustainability and performance of current battery and supercapacitor technology. It harnesses the redox activity of iodide, iodine, and polyiodide species in the confined geometry of nanoporous carbon electrodes. However, current descriptions of the electrochemical reaction mechanism to interconvert these species are elusive. Here we show that electrochemical oxidation of iodide in nanoporous carbons forms persistent solid iodine deposits. Confinement slows down dissolution into triiodide and pentaiodide, responsible for otherwise significant self-discharge via shuttling. The main tools for these insights are in situ Raman spectroscopy and in situ small and wide-angle X-ray scattering (in situ SAXS/WAXS). In situ Raman confirms the reversible formation of triiodide and pentaiodide. In situ SAXS/WAXS indicates remarkable amounts of solid iodine deposited in the carbon nanopores. Combined with stochastic modeling, in situ SAXS allows quantifying the solid iodine volume fraction and visualizing the iodine structure on 3D lattice models at the sub-nanometer scale. Based on the derived mechanism, we demonstrate strategies for improved iodine pore filling capacity and prevention of self-discharge, applicable to hybrid supercapacitors and batteries
Visualising emergent phenomena at oxide interfaces
Knowledge of atomic-level details of structure, chemistry, and electronic
states is paramount for a comprehensive understanding of emergent properties at
oxide interfaces. We utilise a novel methodology based on atomic-scale electron
energy loss spectroscopy (EELS) to spatially map the electronic states tied to
the formation of a two-dimensional electron gas (2DEG) at the prototypical
non-polar/polar / interface. Combined with differential phase
contrast analysis we directly visualise the microscopic locations of ions and
charge and find that 2DEG states and defect states exhibit different
spatial distributions. Supported by density functional theory (DFT) and
inelastic scattering simulations we examine the role of oxygen vacancies in
2DEG formation. Our work presents a general pathway to directly image emergent
phenomena at interfaces using this unique combination of arising microscopy
techniques with machine learning assisted data analysis procedures.Comment: 17 pages, 10 figure
Adatom dynamics and the surface reconstruction of Si(110) revealed using time-resolved electron microscopy
Dislocations in ceramic electrolytes for solid-state Li batteries
High power solid-state Li batteries (SSLB) are hindered by the formation of dendrite-like structures at high current rates. Hence, new design principles are needed to overcome this limitation. By introducing dislocations, we aim to tailor mechanical properties in order to withstand the mechanical stress leading to Li penetration and resulting in a short circuit by a crack-opening mechanism. Such defect engineering, furthermore, appears to enable whisker-like Li metal electrodes for high-rate Li plating. To reach these goals, the challenge of introducing dislocations into ceramic electrolytes needs to be addressed which requires to establish fundamental understanding of the mechanics of dislocations in the particular ceramics. Here we evaluate uniaxial deformation at elevated temperatures as one possible approach to introduce dislocations. By using hot-pressed pellets and single crystals grown by Czochralski method of Li6.4La3Zr1.4Ta0.6O12 garnets as a model system the plastic deformation by more than 10% is demonstrated. While conclusions on the predominating deformation mechanism remain challenging, analysis of activation energy, activation volume, diffusion creep, and the defect structure potentially point to a deformation mechanism involving dislocations. These parameters allow identification of a process window and are a key step on the road of making dislocations available as a design element for SSLB
Impact of Iodine Electrodeposition on Nanoporous Carbon Electrode Determined by EQCM, XPS and In Situ Raman Spectroscopy
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